Conventional power tools powered by electric power are used in a wide range today and the electric power can be supplied by connecting a cable to a receptacle on the wall. The power can also be provided by a battery pack which is easily connected to the tool so that the tools can be portable without limitation by the length of the cable. The users use the tools to output a torque to tighten or loosen objects conveniently, however, the users do not know the exact output torque that is applied to the objects and the information of the value of the output torque is important when dealing with precision machine. Too much torque might hurt the objects on the precision machine, insufficient torque cannot meet requirements for the objects.
The present invention intends to provide a torque detection device for power tools wherein the exact output torque can be displayed in the display device on the tools so that the users can easily control the quality of work.